Bangkok, Thailand — Authorities in Pakistan have detained an Indonesian militant accused of playing a key role in the 2002 Bali bombings and seen as a crucial link between Al Qaeda and its Southeast Asian affiliates.

The US had offered a $1 million reward for information leading to Umar Patek's capture and is likely to have sought access to him in Pakistan, both as a potential source of intelligence on Al Qaeda’s current operations as well as Southeast Asia terror plots.

Until recently, Southeast Asian intelligence officials had thought that Mr. Patek, a slight Javanese-Arab also known as “Little Umar,” was hiding out on Mindanao, the second largest island in the Philippines. His presence in Pakistan raises questions about ongoing collaboration between Southeast Asian militants and Al Qaeda or other Pakistan-based groups.

Patek is also wanted by both Indonesia and the Philippines, where he trained militants and sought haven with extremist groups on Mindanao. On Wednesday, Indonesian police that they were sending a team to Pakistan to follow up on his arrest and may try to bring him home to stand trial.

“Our intelligence team is verifying the information with the Pakistani authorities to confirm if the person arrested was really him," an Indonesian counter-terrorism official, Ansyaad Mbai, told Agence-France Presse. “If it's him, then that's really good news for us.”

The US government hasn’t commented on the detention, and it’s unclear if it was the result of US-Pakistan collaboration against jihadist groups. Security ties between the two countries were strained by the arrest of Raymond Davis, a CIA contractor, who shot two men in Lahore in January and was later released after payments were made to the victims’ families.

Patek is a senior member of Jemaah Islamiyah (JI), a militant group set up in the 1990s by radical clerics and Afghan-trained jihadists from Southeast Asia. The group carried out the 2002 Bali nightclub bombings, which killed 202 people, mostly foreign tourists, and other attacks on Western targets in Indonesia. The most recent incident was twin hotel bombings in Jakarta in July 2009, blamed on a JI splinter group.

'An extraordinary break'

In its statement, the Philippine Army said Patek had been arrested in Pakistan on Jan. 25 (other reports suggest he was detained in March) “together with a Pakistani associate who was assumed to be harboring him.”

“If confirmed, it’s an extraordinary break. We’ve always wondered about the [militant] links not only between the Philippines and Indonesia but also between Southeast Asia and South Asia, especially groups along the Pakistan-Afghanistan border,” says Sidney Jones, a Jakarta-based expert on JI for the International Crisis Group.

Born in 1970, Patek first traveled to Pakistan in 1991 and later joined other Southeast Asian volunteers at an Al Qaeda training camp across the border in Afghanistan, according to Ms. Jones. He later moved to the Philippines, where he married a local Muslim and helped to set up a camp for Malaysian, Indonesian, and Philippine militants, under the wing of the Moro Islamic Liberation Front. Government troops overran the camp in 2000, and the militant group is currently in peace talks with the Philippine government.

Patek returned to Indonesia and helped execute the 2002 bombings, according to the US government. Many of the other key plotters in that attack were later captured or killed, including Hambali, an Indonesian who is in US custody in Guantánamo Bay after being captured in Thailand in 2003.

Patek slipped away in the aftermath of the Bali bombings. Philippine intelligence officials said that he had returned to Mindanao to join Abu Sayyaf, which is fighting US-backed Philippine troops in the Sulu peninsula, a backdoor smuggling route to Malaysia and Indonesia.

US role in Mindanao

US military officials have cited the presence of Patek and other wanted JI militants in Abu Sayyaf strongholds as the reason for continued US troop rotations in Mindanao. Under Philippine law, US soldiers are restricted to noncombat roles, such as intelligence, training, and humanitarian missions.

The Philippine statement linked Patek to more recent JI bombings in Indonesia, including a 2004 attack outside the Australian embassy in Jakarta. However, Jones says there had been no confirmed sightings of Patek in Indonesia since 2002. From 2004 to 2005, he posted articles on an extremist website extolling the virtues of armed struggle in Mindanao.

“[The authorities] will be interested to know when he left Mindanao,” says Jones, adding that authorities will be keen to know how many foreign militants are in the southern Philippines and whether they still have safe havens there.